Emergency Preparedness and Response: School Dismissals to Reduce Transmission of Pandemic Influenza

The CPSTF finding is based on evidence from a systematic review of 67 papers. The systematic review was conducted on behalf of the CPSTF by a team of specialists in systematic review methods, and in research, practice, and policy related to emergency preparedness and response.

During an influenza pandemic, the coordinated closure of schools could be an important community-wide public health action. If implemented efficiently and maintained for an appropriate duration, school dismissals could reduce or delay transmission of infection; reduce the burden of illness on communities, health systems, and providers; provide time to implement additional public health actions (such as distribution of an effective vaccine); and reduce morbidity and mortality caused by the pandemic. The closure of educational facilities for the required duration, however, will involve costs to households and communities, due to social disruption and related economic effects. Against these costs, benefits from reduced morbidity and mortality (and related social and economic effects) could vary, depending on how easily the infection is spread, the severity of illness, and effectiveness of the overall public health response.

In conducting this review, the CPSTF considered the available evidence regarding benefits and costs of coordinated school closures for an extended duration (weeks to months). The CPSTF finding is an assessment of the overall value of coordinated school closures to the community during an influenza pandemic. Many dismissal decisions will be made locally, by school and public health officials who incorporate local considerations and information. Although the decision to close individual schools (especially schools with students at elevated risk for complications of influenza) during high or increasing rates of illness, absenteeism, or public concern remains a local option, such actions alone are unlikely to affect community-wide transmission of pandemic influenza.

• Five studies used historical sources to reconstruct community mitigation actions taken by major cities in the United States and Australia during the 1918 pandemic.
  • Cities that quickly closed schools in combination with other interventions experienced lower regional death rates (by as much as 30-40%), although relaxation of these policies was frequently associated with secondary peaks in pandemic-related mortality.
• Thirty-one studies examined pandemic or seasonal influenza transmission in relationship to school operations. Most described limited evaluation of short term reactive school closures in response the 2009 pandemic H1N1 or outbreaks of seasonal influenza.
  • Several of the studies showed reductions in school or community illness, but few looked at comparisons between schools that were closed and schools that remained open
• Thirty-one published papers described computer-based models of community actions and outcomes during a simulated influenza pandemic.
  • Across a range of simulated pandemic scenarios, pre-emptive, extended duration school dismissals reduced transmission, delayed and blunted peak rates of illness, and reduced hospitalizations and deaths.
  • The combination of school dismissals with additional interventions such as anti-viral distribution programs or additional changes in social distancing, demonstrated an even larger impact on pandemic influenza transmission, illnesses, and deaths.

• The economic evidence included 20 studies:
  • Eleven studies used actual school dismissals and focused on household costs during short term closures.
  • Nine modeling studies examined societal economic costs and benefits from extended school dismissals across a range of influenza pandemic scenarios.
• Simulation models identified substantial costs to school districts, students, parents, and employers with extended school closures irrespective of the impact of the closures on pandemic influenza transmission and illness.
  • In simulations of pandemics with low severity of illness, the costs of extended duration closures exceeded the economic benefits accrued from reduced transmission and illness in the community.
  • In scenarios where transmissibility, severity of illness, and case fatality were high, school dismissals averted substantial morbidity and mortality leading to reduced health care costs, reduced productivity loses associated with work absences, and greater overall quality adjusted life years for the population.
• Two economic simulations of school dismissals combined with additional interventions in response to severe pandemics reported net cost per quality adjusted life year saved within a conservative threshold of $50,000.

• The Task Force notes several limitations in the applicability of the available evidence to school and public health decisions.
  • Unique characteristics of the next pandemic may influence the effectiveness of school dismissals or other public health actions.
  • Public health actions and effects during the 1918 pandemic may not apply now.
  • Findings from community simulation models may not accurately represent real world scenarios.
  • Costs and benefits of short term school dismissals may not be useful predictors of costs and benefits of extended duration closures.
  • Findings from studies of seasonal influenza may not apply to pandemic influenza.
  • Evidence on influenza transmission associated with school openings may not apply to school closure decisions.

CPSTF identified several areas that have limited information. Additional research and evaluation could help answer the following questions and fill remaining gaps in the evidence base. (What are evidence gaps?)

More research is needed to inform future assessments of school dismissals as a pandemic response option.

• Studies documenting the transmission, clinical severity, mitigation actions, and economics of the 2009 H1N1 pandemic should provide information for use as comparison experiences in modeling simulations and economic assessments.
• Future simulations of influenza pandemics should explore the threshold margins of effectiveness of school dismissals (points at which the benefits to costs trade-offs change) based on differences in pandemic impact, school dismissal timing and duration, and the presence or absence of additional community mitigation actions.
• Studies should explore the potential value of school dismissals of shorter duration (1-3 weeks) implemented with the primary intent of reducing the peak burden on health care resources.
• Community simulation models should include organized child care facilities as an additional setting associated with influenza transmission. Simulations should model the timing and completeness of child care closures separately from the timing of school dismissal decisions.

• Studies included in the effectiveness review were as follows:
  • Five retrospective analyses of public health actions taken by different cities during the 1918 pandemic
  • Thirty-one studies of actual school actions (dismissals, holidays, or openings) in the setting of pandemic influenza or seasonal influenza outbreaks
  • Thirty-one papers based on results from community simulation models.
• Thirteen the effectiveness studies or models provided estimates on economic effects of school dismissal interventions, either alone or as part of a combined pandemic response.

Effectiveness Review

Analytic Framework

When starting an effectiveness review, the systematic review team develops an analytic framework. The analytic framework illustrates how the intervention approach is thought to affect public health. It guides the search for evidence and may be used to summarize the evidence collected. The analytic framework often includes intermediate outcomes, potential effect modifiers, potential harms, and potential additional benefits.

Effectiveness Review

• Actual School Dismissals
• Historical Studies
• Modeling Studies

Economic Review

Summary Evidence Table – Economic Review

The number of studies and publications do not always correspond (e.g., a publication may include several studies or one study may be explained in several publications).

Effectiveness Review

Actual Closure, Pandemic Influenza (21 Studies)

Basurto-Davila R, Garza R, Carlino LO, Meltzer MI, Carlino O, et al. Household economic impact and attitudes toward school closures in two cities in Argentina during the 2009 influenza A (H1N1) pandemic. (Unpublished manuscript at the time of review; published: Influenza and Other Respiratory Viruses 2013; 7(6): 1308-15).

Borse RH, Behravesh CB, Dumanovsky T, Zucker JR, Swerdlow DL, Edelson PJ, Choe-Castillo J, Meltzer MI. Closing schools in response to the 2009 pandemic H1N1 influenza A virus (pH1N1) in New York city: economic impact on households. CID 2011;52(Suppl 1): 168-72.

Calatayud L, Kurkela S, Neave PE, Brock A, Perkin S, et al. Pandemic (H1N1) 2009 virus outbreak in a school in London, April/May 2009: an observational study. Epidemiology and Infection 2010; 138(02): 183-91.

CDC. Parental attitudes and experiences during school dismissals related to 2009 influenza A (H1N1) — United States, 2009. MMWR 2010; 59(35): 1131-4.

Chieochansin T, Makkoch J, Suwannakarn K, Payungporn S, Poovorawan Y. Novel H1N1 2009 influenza virus infection in Bangkok, Thailand: effects of school closures. Asian Biomedicine 2009; 3(5): 469-75.

Copeland D, Basurto-Davila R, Chung W, Kurian A, Fishbein D, et al. Effectiveness of a school district closure for pandemic influenza A (H1N1) on acute respiratory illnesses in the community: a natural experiment. (Unpublished manuscript at the time of review; published: Clinical Infectious Diseases 2013; 56(4): 509-16).

Dooyema C, Copeland D, Sinclair J, Shi J, Wilkins M, et al. Factors Influencing School Closure and Dismissal Decisions: Influenza A (H1N1), Michigan 2009. (Unpublished manuscript at the time of review; published: The Journal of School Health 2014; 84(1): 56-62).

Echevarr a-Zuno S, Mej a-Arangur JM, Mar-Obeso AJ, Grajales-Mu iz C, Robles-P rez E, et al. Infection and death from influenza A H1N1 virus in Mexico: a retrospective analysis. The Lancet 2009; 374(9707): 2072-9.

Effler P, Carcione D, Giele C, Dowse G, Goggin L, Mak D. Household responses to pandemic (H1N1) 2009-related school closures, Perth, Western Australia. Emerging Infectious Diseases 2010; 16(2): 205-11.

France AM, Jackson M, Schrag S, Lynch M, Zimmerman C, et al. Household transmission of 2009 influenza A (H1N1) virus after a school based outbreak in New York city, April May 2009. Journal of Infectious Diseases 2010; 201(7): 984-92.

Gift T, Palekar R, Sodha S, Kent C, Fagan R, et al. Household effects of school closure during pandemic (H1N1) 2009, Pennsylvania, USA. Emerging infectious diseases 2010; 16(8): 1315-7.

Health Protection Agency. Preliminary descriptive epidemiology of a large school outbreak of influenza A(H1N1)v in the West Midlands, United Kingdom, May 2009. Euro Surveillance 2009; 14(27): 19264.

Hsueh PR, Lee PI, Chiu AW, Yen MY. Pandemic (H1N1) 2009 vaccination and class suspensions after outbreaks, Taipei City, Taiwan. Emerging Infectious Diseases 2010; 16(8): 1309-11.

Jarquin V, Callahan D, Cohen N, Balaban V, Wang R, et al. Effect of school closure from pandemic (H1N1) 2009, Chicago, Illinois, USA. Emergin Infectious Diseases 2011; 17(4): 751-753.

Kawaguchi R, Miyazono M, Noda T, Takayama Y, Sasai Y, Iso H. Influenza (H1N1) 2009 outbreak and school closure, Osaka Prefecture, Japan. Emerging Infectious Diseases 2009; 15(10): 1685.

Lessler J, Reich NG, Cummings DAT, MHS, New York City Department of Health and Mental Hygiene Swine Influenza Investigation Team. Outbreak of 2009 pandemic influenza A (H1N1) at a New York city school. New England J Medicine 2009; 361(27): 2628-36.

Loustalot F, Silk BJ, Gaither A, Shim T, Lamias M, et al. Household transmission of 2009 pandemic influenza A (H1N1) and nonpharmaceutical interventions among households of high school students in San Antonio, Texas. Clinical Infectious Diseases 2011; 52(suppl 1): S146-53.

Marchbanks TL, Bhattarai A, Fagan RP, Ostroff S, Sodha SV, et al. An outbreak of 2009 pandemic influenza A (H1N1) virus infection in an elementary school in Pennsylvania. Clinical Infectious Diseases 2011; 52(suppl 1): S154-60.

Miller J, Danon L, O’Hagan J, Goldstein E, Lajous M, Lipsitch M. Student behavior during a school closure caused by pandemic influenza A/H1N1. PloS One 2010; 5(5): e10425.

Wallensten A, Oliver I, Lewis D, Harrison S. Compliance and side effects of prophylactic oseltamivir treatment in a school in South West England. Euro Surveillance 2009; 14(30): 19285.

Wu J, Cowling B, Lau EHY, Ip DKM, Ho LM, et al. School closure and mitigation of pandemic (H1N1) 2009, Hong Kong. Emerging Infectious Diseases 2010; 16(3): 538-41.

Actual Closure Due to Seasonal Flu Outbreaks (3 Studies)

CDC. Impact of seasonal influenza-related school closures on families-Southeastern Kentucky, February 2008. MMWR 2009; 58(50): 1405-9.

Cowling B, Lau E, Lam C, Cheng C, Kovar J, et al. Effects of school closures, 2008 winter influenza season, Hong Kong. Emerging Infectious Diseases 2008; 14(10): 1660.

Johnson A, Moore Z, Edelson P, Kinnane L, Davies, et al. Household responses to school closure resulting from outbreak of influenza B, North Carolina. Emerging Infectious Diseases 2008; 14(7): 1024-30.

Actual Closure Due to Other Factors during Influenza Season (5 Studies)

Garza R, Basurto-Davila R, Ortega-Sanchez I, Carlino L, Meltzer M, et al. Effect of winter school breaks on influenza-like illness, Argentina, 2005-2008. (Unpublished manuscript at the time of review; published: Emerging Infectious Diseases 2013; 19(6): 938-44).

Heymann A, Chodick G, Reichman B, Kokia E, Laufer J. Influence of school closure on the incidence of viral respiratory diseases among children and on health care utilization. Pediatric Infectious Diseases J 2004; 7: 675 7.

Heymann AD, Hoch I, Valinsky L, Kokia E, Steinberg DM. School closure may be effective in reducing transmission of respiratory viruses in the community. Epidemiology and Infection 2009; 137(10): 1369-76.

Rodriguez CV, Rietberg K, Baer A, Kwan-Gett T, Duchin J. Association between school closure and subsequent absenteeism during a seasonal influenza epidemic. Epidemiology 2009; 20(6): 787-92.

Wheeler CC, Erhart LM, Jehn ML. Effect of school closure on the incidence of influenza among school-age children in Arizona. Public Health Reports 2010; 125: 851-9.

Actual Closure, Historical Influenza Pandemic Studies (5 Studies)

Bootsma M, Ferguson N. The effect of public health measures on the 1918 influenza pandemic in U.S. cities. PNAS 2007; 18:7588-93.

Caley P, Philp D, McCracken K. Quantifying social distancing arising from pandemic influenza. J R Soc Interface 2007; 5: 631-9.

Hatchett R, Mecher C, Lipsitch M. Public health interventions and epidemic intensity during the 1918 influenza pandemic. PNAS 2007; 18: 7582-7.

Markel H, Lipman H, Navarro J, Sloan A, Michalsen J, et al. Nonpharmaceutical interventions implemented by U.S. cities during the 1918-1919 influenza pandemic. JAMA 2007; 298(6): 644-54.

Stern AM, Cetron MS, Markel H. Closing the schools: lessons from the 1918-19 U.S. influenza pandemic. Health Aff 2009; 28(6): w1066-78.

School Opening/Closing and Impact on Influenza Transmission (2 Studies)

Chao DL, Halloran ME, Longini IM Jr. School Opening Dates Predict Pandemic Influenza A(H1N1) Outbreaks in the United States. Journal of Infectious Diseases 2010;202(6): 877-80.

Earn DJD, He D, Loeb MB, Fonseca K, Lee BE, et al. Effects of school closure on incidence of pandemic influenza in Alberta, Canada. Annals of Internal Medicine 2012; 156: 173-181.

Modeling Studies, Effectiveness of School Dismissal Alone (29 Studies)

Andrad ttir S, Chin W, Goldsman D, Lee ML, Tsui KL, et al. Reactive strategies for containing developing outbreaks of pandemic influenza. (Unpublished manuscript at the time of review; published: BMC Public Health 2011; 11(Suppl1): S1).

Barrett C, Bisset K, Leidig J, Marathe A, Marathe M. Economic and Social Impact of Influenza Mitigation Strategies by Demographic Class. Epidemics 2011; 3(1): 19-31

Carrat F, Luong J, Lao H, Salle AV, Lajaunie C, Wackernagel H. A ‘small-world-like’ model for comparing interventions aimed at preventing and controlling influenza pandemics. BMC Medicine 2006; 4(1): 26.

Cauchemez S, Valleron AJ, Boelle PY, Flahault A, Ferguson NM. Estimating the impact of school closure on influenza transmission from Sentinel data. Nature Letters 2008; 452: 750-755.

Chao DL, Halloran ME, Obenchain VJ, Longini IM, Jr. FluTE, a Publicly Available Stochastic Influenza Epidemic Simulation Model. PLoS Comput Biol 2010; 6(1): e1000656.

Davey V, Glass R. Rescinding community mitigation strategies in an Infl uenza pandemic. Emerg Infect Dis 2008; 14(3): 365-71.

Davey V, Glass R, Min H, Beyeler W, Glass L. Effective, robust design of community mitigation for pandemic influenza: a systematic examination of proposed US guidance. PloS One 2008; 3(7): e2606.

Ferguson NM, Cummings DAT, Fraser C, Cajka JC, Cooley PC, Burke, DS. Strategies for mitigating an influenza pandemic. Nature 2006; 442(7101): 448-52.

Germann T, Kadau K, Longini I, Macken C. Mitigation strategies for pandemic influenza in the United States. Proceedings of the National Academy of Sciences of the United States of America 2006; 103(15): 5935.

Glass K, Barnes B. How much would closing schools reduce transmission during an influenza pandemic? Epidemiology 2007;18(5): 623-28.

Glass R, Glass L, Beyeler W, Min HJ. Targeted social distancing design for pandemic influenza. Emerging Infectious Diseases 2006;12(11):1671-81.

Gojovic M, Sander B, Fisman D, Krahn M, Bauch C. Modelling mitigation strategies for pandemic (H1N1) 2009. Canadian Medical Association Journal; 2009;181(10): 673-80.

Haber M, Shay D, Davis X, Patel R, Jin X, et al. Effectiveness of interventions to reduce contact rates during a simulated influenza pandemic. Emerging Infectious Diseases 2007;13(4): 581-9.

Halder N, Kelso J, Milne G. Analysis of the effectiveness of interventions used during the 2009 A/H1N1 influenza pandemic. BMC Public Health 2010a;10: 168.

Halder N, Kelso J, Milne G. Developing guidelines for school closure interventions to be used during a future influenza pandemic. BMC Infectious Diseases 2010b;10(1): 221.

House T, Baguelin M, van Hoek AJ, Flasche S, White P, et al. Can reactive school closures help critical care provision during the current influenza pandemic? PLoS Currents 2009; Oct 23;1

Kelso J, Milne G, Kelly H. Simulation suggests that rapid activation of social distancing can arrest epidemic development due to a novel strain of influenza. BMC Public Health 2009;9(1): RRN1119.

Lee B, Brown S, Cooley P, Potter M, Wheaton W, et al. Simulating school closure strategies to mitigate an influenza epidemic. Journal of Public Health Management and Practice 2010;16(3): 252-61.

Lofgren ET, Rogers J, Senese M, Fefferman NH. Pandemic Preparedness Strategies for School Systems: Is Closure Really the Only Way? Ann Zool Fennici 2008;45: 449-58.

Milne G, Kelso J, Kelly H, Huband S, McVernon J. A small community model for the transmission of infectious diseases: comparison of school closure as an intervention in individual-based models of an influenza pandemic. PloS One 2008;3(12): e4005.

Morimoto T, Ishikawa H. Assessment of intervention strategies against a novel influenza epidemic using an individual-based model. Environmental Health and Preventive Medicine 2010;15(3): 151-61.

Perlroth DJ, Glass RJ, Davey VJ, Cannon D, Garber AM, Owens DK. Health Outcomes and Costs of Community Mitigation Strategies for an Influenza Pandemic in the United States. Clinical Infectious Diseases 2010;50(2):165-74.

Roberts MG, Baker M, Jennings LC, Sertsou G, Wilson N. A model for the spread and control of pandemic influenza in an isolated geographical region. Journal of The Royal Society Interface 2007;4(13):325-30.

Sander B, Nizam A, Garrison LP, Postma MJ, Halloran ME, Longini IM. Economic Evaluation of Influenza Pandemic Mitigation Strategies in the United States Using a Stochastic Microsimulation Transmission Model. Value in Health 2009;12(2): 226-33.

Sypsal V, Hatzakis A. School closure is currently the main strategy to mitigate influenza A(H1N1)v: a modeling study. Euro Surveillance 2009;14(24).

Vynnycky E, Edmunds WJ. Analyses of the 1957 (Asian) influenza pandemic in the United Kingdom and the impact of school closures. Epidemiology and Infection 2008; 136(2): 166-79.

Yasuda H, Yoshizawa N, Kimura M, Shigematsu M, Matsumoto M, et al. Preparedness for the Spread of Influenza: Prohibition of Traffic, School Closure, and Vaccination of Children in the Commuter Towns of Tokyo. Journal of Urban Health 2008;85(4):619-35.

Yasuda H, Suzuki K. Measures against transmission of pandemic H1N1 influenza in Japan in 2009: simulation model. Euro Surveillance 2009;14(44).

Zhang T, Fu X, Kwoh C, Xiao G, Wong L, et al. Temporal factors in school closure policy for mitigating the spread of influenza. J Public Health Policy 2011; 32(2): 180-97.

Modeling Studies, Effectiveness of School Dismissal + Other Interventions (2 Studies)

Halloran ME, Ferguson NM, Eubank S, Longini IM, Cummings DAT, et al. Modeling targeted layered containment of an influenza pandemic in the United States. Proceedings of the National Academy of Sciences 2008;105(12):4639-44.

Mniszewski SM, Del Valle SY, Stroud PD, Riese JM, Sydoriak SJ. Pandemic Simulation of Antivirals + School Closures: Buying Time Until Strain-Specific Vaccine Is Available. Comput Math Organ Theory 2008;14:209-21.

Effectiveness Review

The following databases were searched through August 2010: WoS, PsycINFO, Medline, JSTOR, Econlit, ERIC, Embase, SOCA, and Google Scholar.

Studies included English language papers that evaluated an actual or modeled school dismissal for seasonal or pandemic influenza and reported one or more health or economic outcomes on the analytic framework. Evaluations of school breaks (vacations, strikes) reporting changes in influenza or respiratory illness outcomesh5 also were included.

Following the search, CDC or review team members suggested additional papers that included unpublished CDC investigations of H1N1 pandemic and unpublished modeling studies completed by January 2011.

Search Terms

• School dismissal; school closure; non-pharmaceutical interventions; influenza; H1N1;social isolation; social distancing
• Disease outbreaks/ prevention & control; quarantine; schools; public policy; absenteeism; models/theoretical; computer simulation

The following considerations are drawn from studies included in the evidence review, the broader literature, and expert opinion.

• A number of potential harms of school dismissals were evaluated in the included evidence, described in the broader published literature, or generated by the team and Task Force discussions.
  • Modeled community simulations recorded substantial reductions in productivity with extended duration closures, including lost income by working parents staying home in order to care for their children.
  • Parents staying home to care for children will include health care workers, placing an additional strain on health care systems.
  • Children may be at home with inadequate supervision during work days.
  • Improvised day care arrangements will likely increase contacts among children and between children and higher risk adults (such as older family members).
  • There may be lost or delayed services for students including school-provided meals and health care.
  • There may be lost or delayed education of students with disruption of educational attainment, grade progression, graduation, and college entry.
  • Closures could lead to an emergence or exacerbation of disparities in income, education, and receipt of school and social services across communities.
• Several of these potential harms could be reduced with appropriate pandemic response planning and implementation.
  • During the 2009 H1N1 pandemic, Congress provided authority for USDA to operate a Pandemic Supplemental Nutrition Assistance Program (P-SNAP)to protect the food security of children who were certified for free- or reduced price school lunches. These children would have missed the school meals during a pandemic emergency that closed schools for 5 consecutive days.
  • During a pandemic, closed schools may provide additional locations for essential services such as medical care and triage, anti-viral distribution, vaccine administration (once available), and distribution of meals to students and families.
• Some basic elements of school closure are routinely handled by households and schools in the United States.
  • Households adjust to the childcare demands of annual summer breaks.
  • Many schools have experience with short-term school closures (in response to weather events).
  • Some school districts provide meals to students over school breaks.
• The U.S. has limited experience, however, with unscheduled and longer duration closures.
• The primary barriers to implementation of these interventions in the United States will be jurisdictional compliance with the timing, coordination, scale, and duration of school closures.
  • Decision-making authority is likely to vary across jurisdictions, creating the potential for additional delay in coordinated action.
  • Although states have emergency powers, the authority may reside in different offices and respond to different local considerations.
  • There may be social and political opposition to the implementation of other community actions, and resistance to maintaining school closures once the pandemic peak has passed.
• In 1918, a number of U.S. cities experienced secondary pandemic peaks following the relaxation of community mitigation actions. To minimize secondary pandemics, the appropriate duration for school closures in a moderate to severe pandemic may depend on the time required to develop and distribute an effective vaccine.
• Following are questions public health decision-makers should consider when deciding whether or not to close schools.
  • What are the characteristics of this pandemic?
  • Is there an effective vaccine in the pipeline?
  • What other interventions are already in place?
  • What other interventions are planned or being considered?
  • Is this the first or a subsequent wave of the pandemic? If school is out of session, is it an option to delay when students return?
  • What is the end game for this pandemic response? When can schools reopen?
  • Can the effects of school closures on disparities be anticipated and reduced?